Recently, an interest in a solid state disk has greatly increased. The solid state disk includes a flash memory, a synchronous dynamic random access memory, and the like.
Since the solid state disk does not require a mechanical operation device such as a motor which is used for the hard disk drive, relatively little heat and noise are emitted during the operation. Additionally, the solid state disk is robust against an external shock, and may achieve a higher data transmission rate than a hard disk drive.
Generally, in opposition to a hard disk drive, the solid state disk provides a better performance when an amount of free space increases, and reduces an amount of consumed power. Also, a great deal of data unnecessarily existing in the solid state disks may cause an increase in internal copy overhead, and an increase in an amount of power consumed. Accordingly, there may be a need to properly delete the unnecessary data.
Also, a cache is used to increase a rate of writing data in the solid state disk, and a rate of reading data from the solid state disk. That is, the cache is used to increase an access rate by storing frequently requested data. However, when predetermined data is stored in the cache, there is a problem in that the predetermined data stored in the cache is, in general, redundantly stored in the solid state disk. That is, the predetermined data stored in the solid state disk may be unnecessary.
Accordingly, there is a need for a technology that may delete data unnecessarily stored in a solid state disk, without loss of data, based on a relation between a cache and the solid state disk.